Dielectric ceramic composition, dielectric ceramic compact and electronic component including the same

ABSTRACT

A dielectric ceramic composition for radiofrequency applications has a crystalline primary component having a perovskite crystal structure, and an auxiliary component. The crystalline primary component is represented by the formula: 
     (1− x )MeTi a O 1+2a   −x Ln(Ma 1/2 Mb 1/2 ) b O (3+3b)/2   
     wherein Me is at least one of Ca and Sr; Ln is a rare earth element; Ma is at least one of Mg and Zn; Mb is at least one of Sn and Zr; x represents a mole fraction of Ln(Ma 1/2 Mb 1/2 ) b O (3+3b/2) ; and a and b represent molar ratios, wherein 0.95≦a≦1.05, 0.9≦b≦1.05, and 0.3≦x≦0.5. The auxiliary component includes B and Si. The composition can be sintered at 1,000° C. or less. An electronic component includes a ceramic element of the dielectric ceramic composition and conductors provided in the interior of the ceramic element.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to dielectric ceramic compositions and dielectric ceramic compacts for radiofrequency applications, for example, dielectric ceramic compacts having high Q values in radiofrequency ranges such as microwave and millimeter-wave ranges and particularly, a dielectric ceramic composition for radiofrequency applications which can be stacked and sintered together with metal electrodes. The present invention also relates to electric components such as a filter and duplexer including the dielectric ceramic compositions or dielectric ceramic compacts.

[0003] 2. Description of the Related Art

[0004] In recent years, dielectric ceramic compacts provided by sintering dielectric ceramic compositions have been widely used in radiofrequency applications, such as filters, duplexers, dielectric resonators and dielectric substrates for monolithic integrated circuits (MICs).

[0005] In order to reduce the sizes of the above products, the dielectric ceramic compositions must satisfy the following requirements:

[0006] (1) A small dielectric constant;

[0007] (2) A small dielectric loss, in other words, a high Q value; and

[0008] (3) A small dependence of the dielectric constant on temperature.

[0009] For example, Japanese Examined Patent Application Publication No. 4-59267 discloses a dielectric ceramic composition represented by the general formula (Zr,Sn)TiO₄. Though this ceramic composition exhibits generally satisfactory properties: (εr is at least 38 and the Q value is at least 9,000), the composition must be fired at a high temperature of at least 1,350° C.

[0010] Use of inexpensive low-resistance metals such as Ag and Cu in internal electrode materials is required for dielectric resonators and the like in order to reduce material cost.

[0011] It is also required for simplifying the production process that the metals used in internal electrodes can be sintered together with dielectric ceramics. In order to achieve cosintering of the dielectric ceramic and the metal internal electrodes, firing must be performed at a temperature that is lower than the melting point of the metal.

[0012] The melting point of an electrode composed of Ag or Cu is generally in the range of about 960 to 1,100° C., which is significantly lower than firing temperatures of 1,300° C. or more applied in known firing processes for the dielectric ceramic compositions; hence, Ag and Cu cannot be used as the internal electrode materials.

[0013] The above-mentioned ceramic composition disclosed in Japanese Examined Patent Application Publication No. 4-59267 requires a high firing temperature of 1,350° C. or more; hence, the composition cannot be sintered with low-resistance metals such as Ag and Cu.

SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a dielectric ceramic composition for radiofrequency applications which can be fired at a low temperature and be sintered with a low-resistance metal used in internal electrodes, and a dielectric ceramic compact which exhibits superior dielectric characteristics: a high dielectric constant and a high Q value.

[0015] Another object of the present invention is to provide electronic components such as a filter comprising the dielectric ceramic composition.

[0016] According to an aspect of the present invention, a dielectric ceramic composition for radiofrequency applications comprises a crystalline primary component having a perovskite crystal structure, and an auxiliary component. The crystalline primary component is represented by the formula:

(1−x)MeTi_(a)O_(1+2a) −xLn(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b)/2)

[0017] wherein Me is at least one of Ca and Sr; Ln is a rare earth element; Ma is at least one of Mg and Zn; Mb is at least one of Sn and Zr; x represents a mole fraction of Ln(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b/2)); and a and b represent molar ratios, wherein a, b, and x are, respectively, within the following ranges: 0.95≦a≦1.05, 0.9≦b≦1.05, and 0.3≦x≦0.5. The auxiliary component comprises B and Si for decreasing the sintering temperature of the dielectric ceramic composition to about 1,000° C. or less.

[0018] The dielectric ceramic composition satisfying the above requirements has a low sintering temperature; thus, it can be sintered with a low-resistance metal used as internal electrodes.

[0019] Furthermore, the dielectric ceramic compact obtained by sintering the dielectric ceramic composition exhibits superior radiofrequency characteristics such as the Q value and dielectric characteristics; hence, electronic components such as a filter and a duplexer using this dielectric ceramic composition exhibit superior characteristics.

[0020] Preferably, the auxiliary component comprises: about 10 to 60 percent by weight of SiO₂; about 5 to 40 percent by weight of B₂O₃; 0 to about 30 percent by weight of Al₂O₃; about 20 to 70 percent by weight of EO; and 0 to about 15 percent by weight of A₂O, wherein E is at least one of Zn and alkaline earth metal elements selected from Mg, Ca, Sr and Ba, and A is at least one alkali metal element selected from Li, Na and K. This dielectric ceramic composition can be more readily sintered with the low-resistance metal. Thus, the dielectric ceramic composition exhibits superior dielectric characteristics, for example, a significantly high Q value.

[0021] Preferably, the auxiliary component is a glass comprising B and Si. By adding a predetermined proportion of the glass comprising B and Si, the dielectric ceramic composition exhibits further desired characteristics.

[0022] Preferably, the content of the primary component is 100 parts by weight and the content of the auxiliary component is in the range of about 1 to 40 parts by weight. The dielectric ceramic composition for radiofrequency applications thereby exhibits desired characteristics.

[0023] Preferably, the dielectric ceramic composition further comprises an additive. The additive is more than 0 up to about 5 parts by weight of CuO or more than 0 up to about 15 parts by weight of TiO₂, or both, with respect to 100 parts by weight of the primary component. The CuO additive within the above range improves sintering ability of the composition. The TiO₂ additive within the above range increases the Q value.

[0024] Preferably, the rare earth element is at least one selected from the group consisting of Y, La, Pr, Nd and Sm. These rare earth elements facilitate the formation of perovskite crystals composed of the primary component, resulting in a high Q value.

[0025] Preferably, in the above formula, Me is Ca and Ma is Mg. These elements facilitate the formation of the perovskite crystal composed of the primary component, resulting in a high Q value.

[0026] According to another aspect of the present invention, an electronic component comprises a ceramic element and conductors provided in the interior of the ceramic element. The ceramic element comprises the above-described dielectric ceramic compact. This electronic component exhibits satisfactory characteristics.

[0027] In this electronic component, the ceramic element may be formed by firing a composite of a plurality of green ceramic sheets comprising the dielectric ceramic composition.

[0028] Preferably, the conductors are formed by firing respective patterns of a conductive paste applied on the respective green ceramic sheets.

[0029] The dielectric ceramic composition according to the present invention can be sintered together with a low-resistance internal electrode material at a low sintering temperature. When this dielectric ceramic composition is used in, for example, a monolithic ceramic electronic component produced through a sintering step of a composite including green ceramic sheets provided with respective internal electrode patterns composed of a conductive paste, the internal conductors can be formed by simultaneously sintering the conductive paste and the green ceramic sheets at a low sintering temperature. Thus, the resulting monolithic ceramic electronic component exhibits superior characteristics.

[0030] Preferably, the conductors comprise Ag or Cu as the major component.

[0031] Preferably, the electronic component is a filter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is an exploded isometric view of an LC filter as an embodiment of a monolithic ceramic electronic component according to the present invention;

[0033]FIG. 2 is an isometric outside view of the LC filter shown in FIG. 1; and

[0034]FIG. 3 is a circuit diagram of the LC filter shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] The dielectric ceramic composition for radiofrequency applications according to the present invention comprises a crystalline primary component having a perovskite crystal structure, and an auxiliary component. The crystalline primary component is represented by the formula:

(1−x)MeTi_(a)O_(1+2a) −xLn(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b)/2)

[0036] wherein Me is at least one of Ca and Sr; Ln is a rare earth element; Ma is at least one of Mg and Zn; Mb is at least one of Sn and Zr; x represents a mole fraction of Ln(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b/2)); and a and b represent molar ratios, wherein a, b, and x are, respectively, within the following ranges: 0.95≦a≦1.05, 0.9≦b≦1.05, and 0.3≦x≦0.5. The auxiliary component comprises B and Si for decreasing the sintering temperature of the dielectric ceramic composition to about 1,000° C. or less.

[0037] If a is outside of the range of 0.95 to 1.05, or if b is outside of the range of 0.9 to 1.05, the Q value is unsatisfactorily low. If x is less than 0.3, the temperature coefficient of the resonant frequency is undesirably large. If x exceeds 0.5, the temperature coefficient of the resonant frequency has a large negative value.

[0038] A dielectric ceramic composition satisfying the above requirements has a low sintering temperature; thus, it can be sintered with a low-resistance metal used as internal electrodes. Furthermore, the dielectric ceramic compact made of the dielectric ceramic composition exhibits superior radiofrequency characteristics, such as Q value and dielectric characteristics; hence, electronic components such as a filter and a duplexer using this dielectric ceramic composition exhibit superior characteristics.

[0039] Preferably, the auxiliary component comprises: about 10 to 60 percent by weight of SiO₂; about 5 to 40 percent by weight of B₂O₃; 0 to about 30 percent by weight of Al₂O₃; about 20 to 70 percent by weight of EO; and 0 to about 15 percent by weight of A₂O, wherein E is at least one of Zn and alkaline earth metal elements selected from Mg, Ca, Sr and Ba, and A is at least one alkali metal element selected from Li, Na and K.

[0040] At an SiO₂ content of less than about 10 percent by weight, the moisture resistance and the Q value decrease. At an SiO₂ content exceeding about 60%, the softening temperature of the auxiliary component such as glass is high, resulting in poor sintering ability, that is, the composition cannot be sintered at about 1,000° C. or less.

[0041] At a B₂O₃ content of less than about 5 percent by weight, the softening temperature of the auxiliary component such as glass is high, resulting in poor sintering ability. At a B₂O₃ content exceeding about 40 percent by weight, the moisture resistance decreases.

[0042] At an Al₂O₃ content exceeding about 30 percent by weight, the softening temperature of the auxiliary component such as glass is high, resulting in poor sintering ability.

[0043] Regarding the alkaline earth metal oxide and zinc oxide, at a content of less than about 20 percent by weight, the softening temperature of the auxiliary component such as glass is high, resulting in poor sintering ability. At a content exceeding about 70 percent by weight, the moisture resistance and the Q value decrease.

[0044] Though addition of alkali metal oxide to the auxiliary component such as glass is effective in decreasing the sintering temperature, the moisture resistance and the Q value decrease at an alkali metal oxide content exceeding about 15 percent by weight. Thus, the alkali oxide metal content is preferably in the range of 0 to about 15 percent by weight.

[0045] Preferably, the auxiliary component is a glass comprising B and Si. By adding a predetermined proportion of the glass comprising B and Si, the dielectric ceramic composition exhibits further desired characteristics.

[0046] Preferably, the content of the primary component is 100 parts by weight and the content of the auxiliary component is in the range of about 1 to 40 parts by weight. The dielectric ceramic composition for radiofrequency applications thereby exhibits desired characteristics.

[0047] Preferably, the dielectric ceramic composition further comprises an additive. The additive is 0 to about 5 parts by weight of CuO or 0 to about 15 parts by weight of TiO₂, or both, with respect to 100 parts by weight of the primary component. The CuO additive improves sintering ability of the composition, but the Q value decreases at a CuO content exceeding about 5 parts by weight. The TiO₂ additive increases the Q value, but the temperature coefficient of the resonant frequency is significantly large at a content exceeding about 15 parts by weight.

[0048] Preferably, the rare earth element is at least one selected from the group consisting of Y, La, Pr, Nd and Sm. These rare earth elements facilitate the formation of the perovskite crystals composed of the primary component, resulting in a high Q value.

[0049] Preferably, Me is Ca and Ma is Mg in the above formula. These elements facilitate the formation of the perovskite crystal composed of the primary component, resulting in a high Q value.

[0050] Using this dielectric ceramic composition for radiofrequency applications, electric components, such as filters and duplexers, having superior characteristics can be readily produced.

[0051]FIGS. 1, 2 and 3 are an exploded isometric view, an isometric outside view and a circuit diagram, respectively, of a monolithic ceramic electronic component according to an embodiment of the present invention.

[0052] This monolithic ceramic electronic component 20 in FIG. 2 is an LC filter. The monolithic ceramic electronic component 20 includes a sintered dielectric ceramic compact 21 having a circuit constituting inductors L and capacitors C therein, as described below. The sintered ceramic compact 21 of the monolithic ceramic electronic component 20 comprises the above-mentioned dielectric ceramic compact made of the dielectric ceramic composition for radiofrequency applications of the present invention. On outer faces of the sintered ceramic compact 21, external electrodes 23 a, 23 b, 24 a and 24 b are formed. An LC circuit shown in FIG. 3 is formed between the external electrodes 23 a, 23 b, 24 a and 24 b.

[0053] The configuration of the sintered ceramic compact 21 and a method for making the same will now be described with reference to FIG. 1.

[0054] An organic vehicle is added to the dielectric ceramic composition according to the present invention to prepare a ceramic slurry. This ceramic slurry is shaped into a green ceramic sheet by any known method such as a doctor blade process. The green ceramic sheet is dried and is punched out into a predetermined size to provide rectangular green ceramic sheets 21 a to 21 m.

[0055] Through holes for via holes are provided in predetermined green ceramic sheets among the green ceramic sheets 21 a to 21 m. A conductive paste is applied onto predetermined green ceramic sheets by screen printing to form coil conductors 26 a and 26 b, internal electrodes for capacitors 27 a, 27 b and 27 c, and coil conductors 26 c and 26 d. The through holes are filled with the conductive paste to form via holes 28.

[0056] The green ceramic sheets 21 a to 21 m are stacked and the stack is compressed in the stacked direction to form a composite. The resulting composite is fired to form a sintered ceramic compact 21 shown in FIG. 2.

[0057] As shown in FIG. 2, external electrodes 23 a, 23 b, 24 a and 24 b are formed on the sintered ceramic compact 21 to prepare the monolithic ceramic electronic component 20. The external electrodes 23 a, 23 b, 24 a and 24 b may be formed by any process, for example, by a thick-film forming process including applying and baking a conductive paste, or a thin-film forming process such as evaporation, plating or sputtering.

[0058] In the monolithic ceramic electronic component (LC filter) 20, the coil conductors 26 a and 26 b of FIG. 1 constitute an inductor unit L1 in FIG. 3, the coil conductors 26 c and 26 d of FIG. 1 constitute another inductor unit L2 in FIG. 3, and the internal electrodes 27 a, 27 b, and 27 c of FIG. 1 constitute capacitors C in FIG. 3.

[0059] In the monolithic ceramic electronic component (LC filter) 20 according to this embodiment, the sintered ceramic compact 21 is formed of the dielectric ceramic composition for radiofrequency applications of the present invention. Hence, the component can be sintered at a low temperature. When a low-melting point metal, for example, Ag or Cu is used in the coil conductors 26 a, 26 b, 26 c and 26 d and the internal electrodes 27 a, 27 b and 27 c for capacitors, the metal can be fired together with the green ceramic sheets. Accordingly, the LC filter can be readily produced. The LC filter is suitable for radiofrequency applications requiring a high relative dielectric constant, a high Q value at radiofrequency, and a small temperature coefficient τf of the resonant frequency.

[0060] The dielectric ceramic composition for radiofrequency applications according to the present invention can be preferably applied to filters and duplexers, as described above. The dielectric ceramic composition can also be applied to dielectric resonators and dielectric substrates for MICs.

EXAMPLES

[0061] The present invention will now be described in further detail with reference to the following examples.

[0062] 1. As starting materials, calcium carbonate (CaCO₃), strontium carbonate (SrCO₃), titanium oxide (TiO₂), rare earth oxides (La₂O₃ etc.), magnesium oxide (MgO), zinc oxide (ZnO) and tin oxide (SnO₂) are prepared.

[0063] 2. These starting materials were formulated to prepare compositions having the following formula:

(1−x)MeTi_(a)O_(1+2a) −xLn(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b)/2)

[0064] Additionally, in Sample 39 (Table 4), Samples 66 to 70 (Table 7), Sample 113 (Table 12), Sample 140 (Table 14), and Samples 141 to 144 (Table 15), a CuO or TiO₂ additive was added to formulate raw materials containing the additive.

[0065] 3. The formulated powders were mixed by a wet process in a ball mill for 16 hours, dehydrated, dried and calcined at 1,100° C. to 1,300° C. for 3 hours. The calcined powdered were pulverized in a ball mill until the particle size became less than 1 μm.

[0066] 4. Meanwhile, BaCO₃, SrCO₃, CaCO₃, MgCO₃, ZnO, Al₂O₃, Li₂CO₃, Na₂CO₃, K₂CO₃, SiO₂ and B₂O₃ were formulated according to the compositions shown in Table 16. The formulated mixtures were each placed into a PtRh crucible and melted at 1,200° C. to 1,600° C. Each melt was quenched and pulverized to form a glass material (powdered glass) as an auxiliary component. It should be noted that the composition represented by G26 in Table 16 could not be formed into glass material.

[0067] 5. Each formulated powder was mixed to form a dielectric ceramic composition, and was compacted under a pressure of 1,000 kgf/cm² into a disk so as to have a diameter of 10 mm and a thickness of 5 mm after firing, and the disk was fired at 900° C. to 1,200° C. for 2 hours to form a dielectric ceramic compact.

[0068] 6. The relative dielectric constant (εr) and the Q value at the resonant frequency (about 1 GHz) of each dielectric ceramic compact were measured by a dielectric resonator method (short-circuited at both ends of a dielectric resonator).

[0069] The results are also shown in Tables 1 to 15. In Tables 1 to 15, asterisked samples represent outside of the present invention, and the others represent within the present invention.

[0070] Tables 1 to 15 show that the dielectric ceramic compacts according to the present invention have relatively high Q values of 10,000 or more and relative dielectric constants of about 25 or more at about 1 GHz.

[0071] Tables 1 to 15 also show that the dielectric ceramic compositions according to the present invention can be sintered at low temperatures of about 1,000° C. or less.

[0072] The dielectric ceramic compositions according to the present invention can be sintered with an inexpensive metal having low resistance such as Ag or Cu as the internal electrode, and the size of a radiofrequency resonator can be reduced by stacking sheets composed of the dielectric ceramic composition.

[0073] Furthermore, electronic components, such as LC filters and duplexers produced using these dielectric ceramic compositions have satisfactory characteristics. Electronic devices such as communication apparatuses using these electronic components also have satisfactory characteristics.

[0074] While the invention has been particularly shown and described with reference to preferred embodiments and examples thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the spirit and the scope of the invention. TABLE 1 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.)  1* Ca Mg La Sn 1.00 1.00 0.25 — G1 10 900 46.3 9.2 51 2 Ca 0.8 Mg La Sn 1.00 1.00 0.30 — G1 10 900 43.4 10.0 27 0.2 Zn 3 Ca Mg La Sn 1.00 1.00 0.30 — G1 10 900 42.6 11.8 33  4* Ca Mg La Sn 0.90 1.00 0.35 — G1 10 900 38.6 6.2 8 5 Ca Mg La Sn 0.95 1.00 0.35 — G1 10 900 38.9 14.3 7  6* Ca Mg La Sn 1.00 0.85 0.35 — G1 10 900 38.9 6.1 9 7 Ca Mg La Sn 1.00 0.90 0.35 — G1 10 900 38.8 16.8 8 8 Ca Mg La Sn 1.00 1.00 0.35 — G1 10 900 38.9 16.9 7 9 Ca Mg La Sn 1.00 1.05 0.35 — G1 10 900 38.7 15.8 8 10* Ca Mg La Sn 1.00 1.10 0.35 — G1 10 900 38.8 5.9 7

[0075] TABLE 2 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 11 Ca Mg La Sn 1.05 1.00 0.35 — G1 10 900 38.9 10.3 7  12* Ca Mg La Sn 1.10 1.00 0.35 — G1 10 900 38.8 3.9 9 13 Ca 0.8 Mg La Sn 1.00 1.00 0.40 — G1 10 900 35.7 19.9 −20 0.2 Zn 14 Ca Mg La Sn 1.00 1.00 0.40 — G1 10 900 35.1 23.9 −17 15 Ca Mg La Sn 1.00 1.00 0.45 — G1 10 900 32.2 21.0 −35 16 Ca Mg La Sn 1.00 1.00 0.50 — G1 10 900 27.2 21.6 −50  17* Ca Mg La Sn 1.00 1.00 0.55 — G1 10 900 23.0 22.2 −70  18* 0.8 Ca Mg La Sn 0.90 1.00 0.35 — G1 10 900 36.5 5.6 10 0.2 Sr 19 0.8 Ca Mg La Sn 0.95 1.00 0.35 — G1 10 900 36.3 11.0 8 0.2 Sr  20* 0.8 Ca Mg La Sn 1.00 0.85 0.35 — G1 10 900 36.1 7.3 9 0.2 Sr

[0076] TABLE 3 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b X Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 21 0.8 Ca Mg La Sn 1.00 0.90 0.35 — G1 10 900 36.3 13.7 11 0.2 Sr 22 0.8 Ca Mg La Sn 1.00 1.00 0.35 — G1 10 900 36.5 14.2 11 0.2 Sr 23 0.8 Ca Mg La Sn 1.00 1.05 0.35 — G1 10 900 36.2 12.8 10 0.2 Sr  24* 0.8 Ca Mg La Sn 1.00 1.10 0.35 — G1 10 900 36.3 6.6 9 0.2 Sr 25 0.8 Ca Mg La Sn 1.00 1.05 0.35 — G1 10 900 36.1 12.4 10 0.2 Sr  26* 0.8 Ca Mg La Sn 1.00 1.10 0.35 — G1 10 900 36.2 4.5 8 0.2 Sr 27 Ca Mg Y Sn 1.00 1.00 0.35 — G1 10 900 37.2 16.7 6 28 Ca Mg 0.1 Y Sn 1.00 1.00 0.35 — G1 10 900 38.6 16.7 7 0.9 La 29 Ca Mg 0.3 Y Sn 1.00 1.00 0.35 — G1 10 900 38.1 16.7 7 0.7 La 30 Ca Mg Pr Sn 1.00 1.00 0.35 — G1 10 900 38.6 17.0 8

[0077] TABLE 4 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 31 Ca Mg 0.1 Pr Sn 1.00 1.00 0.35 — G1 10 900 38.8 10.9 9 0.9 La 32 Ca Mg 0.3 Pr Sn 1.00 1.00 0.35 — G1 10 900 38.4 17.0 8 0.7 La 33 Ca Mg Nd Sn 1.00 1.00 0.35 — G1 10 900 38.3 17.5 8 34 Ca Mg 0.1 Nd Sn 1.00 1.00 0.35 — G1 10 900 38.5 16.6 9 0.9 La 35 Ca Mg 0.3 Nd Sn 1.00 1.00 0.35 — G1 10 900 37.9 16.9 8 0.7 La 36 Ca Mg Sm Sn 1.00 1.00 0.35 — G1 10 900 37.2 17.6 11 37 Ca Mg 0.1 Sm Sn 1.00 1.00 0.35 — G1 10 900 38.3 17.0 10 0.9 La 38 Ca Mg 0.3 Sm Sn 1.00 1.00 0.35 — G1 10 900 37.9 17.2 9 0.7 La 39 Ca Mg La Sn 1.00 1.00 0.35 TiO₂ G1 10 900 39.0 18.5 14 40 Ca Mg La Sn 1.00 1.00 0.35 — G2 10 900 37.9 18.0 9

[0078] TABLE 5 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.)  41* Ca Mg La Sn 1.00 1.00 0.35 — G3 10 900 37.8 18.1 11 42 Ca Mg La Sn 1.00 1.00 0.35 — G4 10 900 37.9 18.2 4  43* Ca Mg La Sn 1.00 1.00 0.35 — G5 10 900 38.4 18.1 4  44* Ca Mg La Sn 1.00 1.00 0.35 — G6 10 900 37.8 16.0 −1 45 Ca Mg La Sn 1.00 1.00 0.35 — G7 10 900 39.5 14.0 −6 46 Ca Mg La Sn 1.00 1.00 0.35 — G8 10 900 38.5 16.0 3  47* Ca Mg La Sn 1.00 1.00 0.35 — G9 10 900 38.4 12.0 6 48 Ca Mg La Sn 1.00 1.00 0.35 — G10 10 900 38.8 16.0 6 49 Ca Mg La Sn 1.00 1.00 0.35 — G11 10 900 38.8 15.5 5 50 Ca Mg La Sn 1.00 1.00 0.35 — G12 10 900 39.5 17.0 2

[0079] TABLE 6 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.)  51* Ca Mg La Sn 1.00 1.00 0.35 — G13 10 900 38.8 16.5 9 52 Ca Mg La Sn 1.00 1.00 0.35 — G14 10 900 40.1 11.1 13 53 Ca Mg La Sn 1.00 1.00 0.35 — G15 10 900 39.4 12.4 7 54 Ca Mg La Sn 1.00 1.00 0.35 — G16 10 900 39.2 15.2 9 55 Ca Mg La Sn 1.00 1.00 0.35 — G17 10 900 38.9 15.9 7 56 Ca Mg La Sn 1.00 1.00 0.35 — G18 10 900 36.9 13.9 2  57* Ca Mg La Sn 1.00 1.00 0.35 — G19 10 900 35.8 13.0 −1 58 Ca Mg La Sn 1.00 1.00 0.35 — G20 10 900 39.7 15.2 −2 59 Ca Mg La Sn 1.00 1.00 0.35 — G21 10 900 39.0 15.5 2 60 Ca Mg La Sn 1.00 1.00 0.35 — G22 10 900 37.5 15.3 4

[0080] TABLE 7 Auxiliary Glass Sintering Relative Q Value × Content Type of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Auxiliary (wt %) Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 61 Ca Mg La Sn 1.00 1.00 0.35 — — G23 10 900 37.5 16.2 6  62* Ca Mg La Sn 1.00 1.00 0.35 — — G14 0.5 1000  ** ** ** 63 Ca Mg La Sn 1.00 1.00 0.35 — — G14 1 1000  45.0 22.0 10 64 Ca Mg La Sn 1.00 1.00 0.35 — — G12 40 900 30.2 10.0 −10  65* Ca Mg La Sn 1.00 1.00 0.35 — — G12 50 900 26.8 6.2  −15 66 Ca Mg La Sn 1.00 1.00 0.35 TiO₂ 15 G1 10 900 42.0 15.0 35  67* Ca Mg La Sn 1.00 1.00 0.35 TiO₂ 20 G1 10 900 45.0 14.0 55 68 Ca Mg La Sn 1.00 1.00 0.35 CuO  5 G1 10 900 40.2 10.1 −15  69* Ca Mg La Sn 1.00 1.00 0.35 CuO 10 G1 10 900 43.0 2.0  −30 70 Ca Mg La Sn 1.00 1.00 0.35 CuO  1 G1 10 900 39.9 15.0 7

[0081] TABLE 8 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.)  71* Ca Mg La Zr 1.00 1.00 0.275 — G1 10 900 51.5 8.8 50 72 Ca 0.8 Mg La Zr 1.00 1.00 0.30 — G1 10 900 49.5 11.3 36 0.2 Zn 73 Ca Mg La Zr 1.00 1.00 0.30 — G1 10 900 48.9 12.6 40 74 Ca Mg La Zr 1.00 1.00 0.325 — G1 10 900 46.8 14.8 30 75 Ca Mg La Zr 1.00 1.00 0.35 — G1 10 900 44.4 16.6 24 76 Ca Mg La Zr 1.00 1.00 0.375 — G1 10 900 42.0 17.0 9  77* Ca Mg La Zr 0.90 1.00 0.40 — G1 10 900 40.3 7.3 −2 78 Ca Mg La Zr 0.95 1.00 0.40 — G1 10 900 40.4 16.1 −2  79* Ca Mg La Zr 1.00 0.85 0.40 — G1 10 900 40.3 8.6 −3 80 Ca Mg La Zr 1.00 0.90 0.40 — G1 10 900 40.3 18.1 −1

[0082] TABLE 9 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 81 Ca Mg La Zr 1.00 1.00 0.40 — G1 10 900 40.4 17.8 −2 82 Ca Mg La Zr 1.00 1.05 0.40 — G1 10 900 40.2 16.6 −1  83* Ca Mg La Zr 1.00 1.10 0.40 — G1 10 900 40.3 7.0 −3 84 Ca Mg La Zr 1.05 1.00 0.40 — G1 10 900 40.3 13.6 −2  85* Ca Mg La Zr 1.10 1.00 0.40 — G1 10 900 40.2 5.9 −1 86 Ca Mg La Zr 1.00 1.00 0.425 — G1 10 900 38.1 18.5 −18 87 Ca 0.8 Mg La Zr 1.00 1.00 0.425 — G1 10 900 38.8 16.3 −20 0.2 Zn 88 Ca Mg La Zr 1.00 1.00 0.45 — G1 10 900 36.5 19.0 −30 89 Ca Mg La Zr 1.00 1.00 0.475 — G1 10 900 35.0 19.8 −31 90 Ca Mg La Zr 1.00 1.00 0.50 — G1 10 900 32.8 20.9 −50

[0083] TABLE 10 Type of Type Glass Sintering Relative Q Value × Auxiliary of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.)  91* Ca Mg La Zr 1.00 1.00 0.55 — G1 10 900 30.9 21.3 −65  92* 0.8 Ca Mg La Zr 0.90 1.00 0.40 — G1 10 900 38.2 7.2 0 0.2 Sr 93 0.8 Ca Mg La Zr 0.95 1.00 0.40 — G1 10 900 38.3 11.8 0 0.2 Sr  94* 0.8 Ca Mg La Zr 1.00 0.85 0.40 — G1 10 900 38.2 4.6 1 0.2 Sr 95 0.8 Ca Mg La Zr 1.00 0.90 0.40 — G1 10 900 38.2 12.8 0 0.2 Sr 96 0.8 Ca Mg La Zr 1.00 1.00 0.40 — G1 10 900 38.3 14.3 1 0.2 Sr 97 0.8 Ca Mg La Zr 1.00 1.05 0.40 — G1 10 900 38.3 13.4 0 0.2 Sr  98* 0.8 Ca Mg La Zr 1.00 1.10 0.40 — G1 10 900 38.2 6.4 1 0.2 Sr 99 0.8 Ca Mg La Zr 1.05 1.00 0.40 — G1 10 900 38.3 10.2 1 0.2 Sr 100* 0.8 Ca Mg La Zr 1.10 1.00 0.40 — G1 10 900 38.2 4.3 2 0.2 Sr

[0084] TABLE 11 Type of Glass Sintering Relative Q Value Auxiliary Type of Content Temp. Dielectric × 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 101 Ca Mg Y Zr 1.00 1.00 0.40 — G1 10 900 39.4 17.2 −2 102 Ca Mg 0.1 Y Zr 1.00 1.00 0.40 — G1 10 900 39.4 17.0 −2 0.9 La 103 Ca Mg 0.3 Y Zr 1.00 1.00 0.40 — G1 10 900 40.2 16.7 −3 0.7 La 104 Ca Mg Pr Zr 1.00 1.00 0.40 — G1 10 900 39.8 17.3 −2 105 Ca Mg 0.1 Pr Zr 1.00 1.00 0.40 — G1 10 900 40.2 17.2 −1 0.9 La 106 Ca Mg 0.3 Pr Zr 1.00 1.00 0.40 — G1 10 900 39.9 17.0 −2 0.7 La 107 Ca Mg Nd Zr 1.00 1.00 0.40 — G1 10 900 39.6 18.1 −3 108 Ca Mg 0.1 Nd Zr 1.00 1.00 0.40 — G1 10 900 40.1 17.8 −2 0.9 La 109 Ca Mg 0.3 Nd Zr 1.00 1.00 0.40 — G1 10 900 40.2 17.7 −2 0.7 La 110 Ca Mg Sm Zr 1.00 1.00 0.40 — G1 10 900 38.9 17.3 1

[0085] TABLE 12 Type of Glass Sintering Relative Q Value Auxiliary Type of Content Temp. Dielectric × 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 111 Ca Mg 0.1 Sm Zr 1.00 1.00 0.40 — G1 10 900 39.9 17.2 0 0.9 La 112 Ca Mg 0.3 Sm Zr 1.00 1.00 0.40 — G1 10 900 39.5 17.0 0 0.7 La 113 Ca Mg La Zr 1.00 1.00 0.40 TiO₂ G1 10 900 41.0 19.0 3 (5 wt. %) 114 Ca Mg La Zr 1.00 1.00 0.40 — G2 10 900 39.5 18.0 0 115* Ca Mg La Zr 1.00 1.00 0.40 — G3 10 900 39.5 19.8 2 116 Ca Mg La Zr 1.00 1.00 0.40 — G4 10 900 39.4 21.1 −5 117* Ca Mg La Zr 1.00 1.00 0.40 — G5 10 900 40.1 20.0 −5 118* Ca Mg La Zr 1.00 1.00 0.40 — G6 10 900 39.8 16.8 −10 119 Ca Mg La Zr 1.00 1.00 0.40 — G7 10 900 41.0 13.5 −15 120 Ca Mg La Zr 1.00 1.00 0.40 — G8 10 900 40.5 17.0 −5

[0086] TABLE 13 Type of Glass Sintering Relative Q Value Auxiliary Type of Content Temp. Dielectric × 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 121* Ca Mg La Zr 1.00 1.00 0.40 — G9 10 900 40.4 12.0 −3 122 Ca Mg La Zr 1.00 1.00 0.40 — G10 10 900 40.5 17.2 −3 123 Ca Mg La Zr 1.00 1.00 0.40 — G11 10 900 40.3 16.8 −4 124 Ca Mg La Zr 1.00 1.00 0.40 — G12 10 900 41.2 18.0 −7 125* Ca Mg La Zr 1.00 1.00 0.40 — G13 10 900 40.5 17.1 0 126 Ca Mg La Zr 1.00 1.00 0.40 — G14 10 900 41.6 12.0 4 127 Ca Mg La Zr 1.00 1.00 0.40 — G15 10 900 40.4 13.5 −2 128 Ca Mg La Zr 1.00 1.00 0.40 — G16 10 900 40.4 15.6 0 129 Ca Mg La Zr 1.00 1.00 0.40 — G17 10 900 39.9 16.5 −2 130 Ca Mg La Zr 1.00 1.00 0.40 — G18 10 900 38.5 14.8 −7

[0087] TABLE 14 Glass Sintering Relative Q Value Auxiliary Type of Content Temp. Dielectric × 1000 τf Sample Me Ma Ln Mb a b x Component Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 131* Ca Mg La Zr 1.00 1.00 0.40 — G19 10 900 38.0 14.3 −10 132 Ca Mg La Zr 1.00 1.00 0.40 — G20 10 900 41.0 16.0 −10 133 Ca Mg La Zr 1.00 1.00 0.40 — G21 10 900 40.3 17.0 −7 134 Ca Mg La Zr 1.00 1.00 0.40 — G22 10 900 40.0 16.2 −5 135 Ca Mg La Zr 1.00 1.00 0.40 — G23 10 900 39.9 17.8 −2 136* Ca Mg La Zr 1.00 1.00 0.40 — G14 0.5 1000 ** ** ** 137 Ca Mg La Zr 1.00 1.00 0.40 — G14 1 1000 47.0 23.1 2 138 Ca Mg La Zr 1.00 1.00 0.40 — G12 40 900 31.1 10.1 −18 139* Ca Mg La Zr 1.00 1.00 0.40 — G12 50 900 27.0 5.8 −25 140 Ca Mg La Zr 1.00 1.00 0.40 TiO₂ G1 10 900 42.5 19.0 30 (15 w %)

[0088] TABLE 15 Auxiliary Q Type of Component Type Glass Sintering Relative Value × Auxiliary Content of Content Temp. Dielectric 1000 τf Sample Me Ma Ln Mb a b x Component (wt %) Glass (wt %) (° C.) Constant 1 GHz (ppm/° C.) 141* Ca Mg La Zr 1.00 1.00 0.40 TiO₂ 20 G1 10 900 43.2 18.5 55 142 Ca Mg La Zr 1.00 1.00 0.40 CuO 5 G1 10 900 41.2 10.5 −20 143* Ca Mg La Zr 1.00 1.00 0.40 CuO 10 G1 900 10 44.0 2.4 −30 144 Ca Mg La Zr 1.00 1.00 0.40 CuO 1 G1 10 900 41.8 18.9 0 145 Ca Mg La Zr 1.00 1.00 0.40 — — G24 10 900 35.0 23.0 −16 146 Ca Mg La Zr 1.00 1.00 0.40 — — G25 15 900 30.0 15.0 −20

[0089] TABLE 16 SiO₂ B₂O₃ K₂O Li₂O Na₂O BaO SrO MgO CaO ZnO Al₂O₃ G1 25 30 — 10 — — — — — 35 — G2 10 40 — 10 — — — — — 40 — G3* 5 40 — 10 — — — — — 45 — G4 50 20 — 10 — — — — — 20 — G5* 70 10 — 10 — — — — — 10 — G6* 50 2 — 15 — — — — — 33 — G7 40 5 — 15 — 20 — — — 20 — G8 20 50 — 10 — — — — — 20 — G9* 10 70 — 10 —  5 — — — 10 — G10 25 30 10 — — — — — — 35 — G11 25 30 — — 10 — — — — 35 — G12 25 40 — — — — — — — 35 — G13* 15 30 — 20 — — — — — 35 — G14 25 35 — 10 — 30 — — — — — G15 25 35 — 10 — — 30 — — — — G16 25 35 — 10 — — — 30 — — — G17 25 35 — 10 — — — — 30 — — G18 15 10 —  5 — — — — — 70 — G19* 10 5 —  5 — — — — — 80 — G20 25 30 — 10 — — 20 — — 15 — G21 25 30 — 10 — — — 20 — 15 — G22 25 30 — 10 — — — — 15 20 — G23 25 30 —  5 — — — 10 10 20 — G24 24 30 — 10 — — — — — 35  1 G25 10 20 — 10 — — — — — 30 30 G26* 5 20 — 10 — — — — — 15 50 

What is claimed is:
 1. A dielectric ceramic composition for radiofrequency applications comprising a crystalline primary component having a perovskite crystal structure and an auxiliary component, wherein the crystalline primary component is represented by the formula: (1−x)MeTi_(a)O_(1+2a) −xLn(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b)/2) in which Me is at least one of Ca and Sr; Ln is a rare earth element; Ma is at least one of Mg and Zn; Mb is at least one of Sn and Zr; x represents a mole fraction of Ln(Ma_(1/2)Mb_(1/2))_(b)O_((3+3b)/2); and and wherein a, b, and x are, respectively, 0.95≦a≦1.05,0.9≦b≦1.05, and 0.3≦x≦0.5, and wherein the auxiliary component comprises B and Si.
 2. The dielectric ceramic composition according to claim 1, wherein the auxiliary component is a glass comprising B and Si.
 3. The dielectric ceramic composition according to claim 2, wherein the auxiliary component comprises: about 10 to 60 percent by weight of SiO₂; about 5 to 40 percent by weight of B_(2O) ₃; 0 to about 30 percent by weight of Al₂O₃; about 20 to 70 percent by weight of EO; and 0 to about 15 percent by weight of A₂O, wherein E is at least one of Zn or an alkaline earth metal element, and A is at least one alkali metal element.
 4. The dielectric ceramic composition according to claim 3, wherein the content of the auxiliary component is in the range of about 1 to 40 parts by weight per 100 parts by weight of the primary component.
 5. The dielectric ceramic composition according to claim 4, further comprising an additive which is at least one of CuO and TiO₂, in an amount with respect to 100 parts by weight of the primary component of up to about 5 parts by weight of CuO and up to about 15 parts by weight of TiO₂.
 6. The dielectric ceramic composition according to claim 5, wherein the rare earth element is at least one member selected from the group consisting of Y, La, Pr, Nd and Sm.
 7. The dielectric ceramic composition according to claim 6, wherein Me is Ca and Ma is Mg.
 8. The dielectric ceramic composition according to claim 1, further comprising an additive which is at least one of CuO and TiO₂, in an amount with respect to 100 parts by weight of the primary component of up to about 5 parts by weight of CuO and up to about 15 parts by weight of TiO₂.
 9. The dielectric ceramic composition according to claim 1, wherein the rare earth element is at least one member selected from the group consisting of Y, La, Pr, Nd and Sm.
 10. The dielectric ceramic composition according to claim 1, wherein Me is Ca and Ma is Mg.
 11. The dielectric ceramic composition according to claim 1, wherein the auxiliary component comprises: about 10 to 60 percent by weight of SiO₂; about 5 to 40 percent by weight of B₂O₃; 0 to about 30 percent by weight of Al₂O₃; about 20 to 70 percent by weight of EO; and 0 to about 15 percent by weight of A₂O, wherein E is at least one of Zn or an alkaline earth metal element, and A is at least one alkali metal element.
 12. A dielectric ceramic compact for radiofrequency applications comprising a sintered dielectric ceramic composition according to claim
 7. 13. An electronic component comprising a ceramic element having at least one conductor disposed in the interior of the ceramic element, wherein the ceramic element is a sintered composite of a plurality of green ceramic sheets comprising a dielectric ceramic compact according to claim
 12. 14. The electronic component according to claim 13, wherein the conductor comprises Ag or Cu.
 15. A dielectric ceramic compact for radiofrequency applications comprising a sintered dielectric ceramic composition according to claim
 1. 16. An electronic component comprising a ceramic element having at least one conductor disposed in the interior of the ceramic element, wherein the ceramic element comprises a dielectric ceramic compact according to claim
 15. 17. An electronic component according to claim 16, wherein the ceramic element is a sintered composite of a plurality of green ceramic sheets comprising said dielectric ceramic compact.
 18. The electronic component according to claim 17, wherein the conductor is a fired pattern of a conductive paste disposed on a sintered green ceramic sheet.
 19. The electronic component according to claim 18, wherein the conductor comprises Ag or Cu.
 20. The electronic component according to claim 15, wherein the electronic component is a filter. 